The diagnostic device known as magnetic resonance imaging (MRI) has become an invaluable tool for imaging and exploring the internal body without surgery. MRI has the ability to distinguish healthy and diseased tissue, fat and muscle, and between adjacent structures within the body which other modalities cannot demonstrate. MRI utilizes safe radio waves and a magnetic field to generate the images.
In operation, a typical MRI apparatus relies upon hydrogen protons which have a dipole movement and therefore behave as would a magnetic compass. In MRI scanning, the MRI apparatus operates as a large magnet wherein the protons align with the strong magnetic field but are easily disturbed by a brief radio frequency pulse so as to alter their alignment. As the protons return to their orientation with the magnetic field, they release energy of a radio frequency. The released energy is detected and processed for display according to the signal intensity of each issue.
The magnetic coils of the MRI apparatus are permanently fixed within a large structure so as to form a large magnet with a very confining entrance known as the bore. A patient is placed upon a scanner table that is integrated with the MRI apparatus and slid into the middle of the bore. The problem with the bore is the extremely small area for placement of the patient which leads to anxiety. The large and ominous appearance of the scanner together with harsh low monotone sounds which includes both soft and loud thumping, produces an erie and unnatural experience for the patient. Any patient who exhibits claustrophobic tendencies would require sedation before entering the bore. If the patient is above average in size, the problem is exasperated.
It is well known that familiarity of surroundings reduces anxiety. The introduction of familiar images to a person placed within a confining area, such as the MRI bore, will reduce if not eliminate anxiety and certain claustrophobic tendencies of various patients. This reduction can eliminate the need for medicating the patient or the need for a restraining device, all of which may have an adverse effect on a diagnostic test. Thus, a patient who is able to listen to a family member, soft music, or watch a familiar television program will have sufficient distractions so as to avoid concentrating on the immediate surroundings which lead to increased anxiety.
A problem with introducing conventional audio or video signals into an MRI apparatus is that the device is based upon the use of radio frequency which will disrupt signal modulation. Further, the inner area of the bore produces a magnetic field which will draw metal items when magnetized. For this reason, the audio or video signal must be in a form that is not affected by the radio frequency and transmission by a mechanism that is not easily magnetized.
An attempt to address this problem is found in U.S. Pat. No. 4,901,141 which utilizes a fiber optic taper positioned within the bore of an MRI apparatus. A CRT produced image is delivered to the fiber optic taper through a coherent image guide. The fiber optic taper expands the end of the image guide so as to provide a larger viewing surface for the patient. The problem with the fiber optic taper is that it is stationary and the patient must be positioned in a fixed location so as to be able to see the end of the optic taper. Further, to prevent distortion the patient must be located directly beneath the isocenter of the taper. Thus, the disclosure does not address different size patients, patient positioning, or near and far sighted patients. For instance, a tall person may lay with their head partially outside the bore during diagnostics of the lower body whereas a child may be well encapsulated by the bore, neither of which could properly see a fixed fiber optic taper. In addition, the use of a fixed taper will interfere with auxiliary coils, such as head and c-spine coils, that require close proximity to the body. Current construction of head and c-spine coils is such that the visual field as needed for viewing a fixed positioned fiber taper is either obscured or completely blocked if the fiber taper is utilized.
Yet another known device utilized in combination with an MRI apparatus for purposes of patient comfort is a mirror optical system mounted on a spectacle frame and secured to the patient's head. In operation, the patient lies on the scanner table wearing the optical mirror system so that the patient can view over their head so as to watch a television set placed outside of the bore. The mirror mounted spectacles allow use of a head coil, c-spine, or other skin surface mounted coils. A problem with the spectacle mounted mirror system is that it blocks forward viewing and does not accommodate image tilting should the patient turn their head.
Thus, what is lacking in the art is a single device that provides the clarity of optics, the adjustability of corrective lenses, vision viewing at any location of the MRI apparatus, and the ability to provide true stereoscopic vision to the patient allowing the operator to induce visual stimuli to either eye of the patient.